early 15c., "pains taken to attain an object," literally "in duty," from phrase put (oneself) in dever "make it one's duty" (a partial translation of Old French mettre en deveir "put in duty"), from Old French dever "duty," from Latin debere "to owe" (see debt). One's endeavors meaning one's "utmost effort" is from late 15c.

chiefly British English spelling of endeavor (q.v.); for spelling, see -or. Related: Endeavoured; endeavoring; endeavours. The U.S. space shuttle was spelled this way because it was named for the HMS Endeavour, Capt. Cook's ship.

"particular to a people or locality," 1650s (endemical), with -ic + Greek endemos "native, dwelling in (a place), of or belonging to a people," from en "in" (see en- (2)) + demos "people, district" (see demotic). From 1660s as a noun.

late 14c., from Old French endive (14c.), from Medieval Latin endivia or a related Romanic source, from Latin intibus. This probably is connected in some way with Medieval Greek entybon, which Klein says is perhaps of Eastern origin (compare Egyptian tybi "January," the time the plant grows in Egypt). Century Dictionary says Arabic hindiba is "appar. of European origin."

Old English endeleas "boundless, eternal;" see end (n.) + -less. Compare Old Saxon endilos, Dutch eindeloos, German endlos. Related: Endlessly; endlessness. Old English used endeleasnes for "infinity, eternity."

c. 1200, "from end to end, lengthwise; through or over the length of," from Old English andlang "from end to end, lengthwise" (see along) with Middle English substitution of ende (see end (n.)) for first element. Meaning "at full length, horizontally" is from early 15c. In Middle English frequently paired with overthwart and together meaning "lengthwise and crosswise," hence "in all directions."

"marriage within the tribe or group," 1865, from endo- on model of polygamy. Related: Endogamous (1865). Opposed to exogamy. Apparently both were coined by Scottish anthropologist John Ferguson McLennan (1827-1881) in "Primitive Marriage."

To this law, the converse of caste, forbidding marriage within the tribe, Mr. M'Lennan has given the name of exogamy: while, instead of caste, since that word involves notions unconnected with marriage, he has used the correlative word -- endogamy. [review in "The Lancet," March 25, 1865]

1940 as one of W.H. Sheldon's three types of human bodies, from endo- + -morph, from Greek morphe "form" (see Morpheus). Earlier, "a mineral encased in the crystal of another mineral" (1874). Related: Endomorphic.

"chemical which occurs naturally in the brain and works like morphine," 1975, from French endorphine. First element from endogène "endogenous, growing within" (see endo- + genus); second element from morphine.

c. 1400, endosse "confirm or approve" (a charter, bill, etc.), originally by signing or writing on the back of the document, from Old French endosser (12c.), literally "to put on the back," from en- "put on" (see en- (1)) + dos "back," from Latin dossum, variant of dorsum "back" (see dorsal). Assimilated 16c. in form to Medieval Latin indorsare. Figurative sense of "confirm, approve" is recorded in English first in 1847. Related: Endorsed; endorsing.

You can endorse, literally, a cheque or other papers, &, metaphorically, a claim or argument, but to talk of endorsing material things other than papers is a solecism. [Fowler]

beautiful youth, son of Jupiter and Calyce, beloved by Moon-goddess Selene, from Greek, perhaps literally "diver, plunger," from endyein "to enter into, sink into, plunge, dive," which was used in reference to the sun or stars setting into the sea. On this theory, he originally was a solar deity, a personification of the setting sun.

early 13c., "one hateful toward and intent on harming (someone)," from Old French enemi (12c., Modern French ennemi), earlier inimi (9c.) "enemy, adversary, foe; demon, the Devil," from Latin inimicus "an enemy," literally "an unfriend," noun use of adjective meaning "hostile, unfriendly" (source also of Italian nemico, Catalan enamic, Spanish enemigo, Portuguese inimigo), from in- "not" (see in- (1)) + amicus "friend" related to amare "to love" (see Amy). From c. 1300 in English as "adversary of God, unbeliever, heathen, anti-Christian;" late 14c. as "the Devil;" also late 14c. as "member of an armed, hostile body in a war, feud, etc.;" of the opposing military forces as a whole, from c. 1600. From mid-14c. as an adjective.

Most Indo-European words for "personal enemy" cover also "enemy in war," but certain languages have special terms for the latter, such as Greek polemioi (distinct from ekhthroi), Latin hostis, originally "stranger" (distinct from inimicus), Russian neprijatel' (distinct from vrag). Russian vrag (Old Church Slavonic vragu) is cognate with Lithuanian vargas "misery" (see urge (v.)), and probably is related to Proto-Germanic *wargoz, source of Old Norse vargr "outlaw," hence "wolf;" Icelandic vargur "fox;" Old English wearg "criminal, felon;" which likely were the inspirations for J.R.R. Tolkien's warg as the name of a kind of large ferocious wolf in "The Hobbit" (1937) and "Lord of the Rings." Related: Enemies.

1650s, "powerful in operation," from Greek energetikos "active," from energein "to work, be in action, act upon" (see energy). Of persons, "active," in English from 1796 (energetical "operative" is from c. 1600; from 1630s as "full of energy," while energical is attested from 1560s). Related: Energetically.

Used by Aristotle with a sense of "actuality, reality, existence" (opposed to "potential") but this was misunderstood in Late Latin and afterward as "force of expression," as the power which calls up realistic mental pictures. Broader meaning of "power" in English is first recorded 1660s. Scientific use is from 1807. Energy crisis first attested 1970.